package start.demo01;

import org.junit.Test;

import java.security.MessageDigest;
import java.util.Random;

/**
 * MD5加密工具类
 */
public class MD5 {
    private final static String[] hexDigits = {"0", "1", "2", "3", "4", "5",
            "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};

    /**
     * 转换字节数组为16进制字符串
     *
     * @param b 字节数组
     * @return 16进制字符串
     */

    public static String byteArrayToHexString(byte[] b) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++) {
            resultSb.append(byteToHexString(b[i]));
        }
        return resultSb.toString();
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0)
            n = 256 + n;
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    public static String MD5Encode(String origin) {
        String resultString = null;

        try {
            resultString = new String(origin);
            MessageDigest md = MessageDigest.getInstance("MD5");
            resultString = byteArrayToHexString(md.digest(resultString
                    .getBytes()));
        } catch (Exception ex) {

        }
        return resultString;
    }

    public static String MD5Encode(String origin, int i) {
        String resultString = null;

        try {
            resultString = new String(origin);
            MessageDigest md = MessageDigest.getInstance("MD5");
            resultString = byteArrayToHexString(md.digest(resultString
                    .getBytes()));
        } catch (Exception ex) {

        }
        return resultString;
    }

    @Test
    public void RandomDigit() {
        Random r = new Random(1);
        for (int i = 0; i < 5; i++) {
            int ran1 = r.nextInt(100);
            System.out.println(ran1);
        }
    }

    @Test
    public void RandomDigit2() {//产生数字
    	StringBuilder str=new StringBuilder();
        for (int i = 0; i < 4; i++) {
			double d = Math.random();//它返回的是0(包含)到1(不包含)之间的double值
			int n = (int)(d*10);
            str.append(n+"");
        }
		System.out.println(str.toString());
    }
    @Test
    public void RandomDigit3() {//产生字符
    	StringBuilder str=new StringBuilder();
    	StringBuilder str2=new StringBuilder();
        for (int i = 0; i < 4; i++) {
			double d = Math.random();//它返回的是0(包含)到1(不包含)之间的double值
			int n = (int)(d*25)+65;//大写
			int x=  (int)(d*25)+97;//小写
            str.append((char)n);
            str2.append((char)x);
        }
		System.out.println(str.toString());
		System.out.println(str2.toString());
    }
    @Test
    public void RandomDigit4() {//产生大小写混合字符
    	StringBuilder str=new StringBuilder();
        for (int i = 0; i < 4; i++) {
			double d = Math.random();//它返回的是0(包含)到1(不包含)之间的double值
			int n = (int)(d*58)+65;//大写
			if(n>90&&n<97)
				n+=6;
            str.append((char)n);
        }
		System.out.println(str.toString());
    }
}